There's supposedly some neurological studies out there about the origins of transness, but they're not very good:

• Most of them have small sample sizes

• They often involve brain parts that are not very well understood, and brain properties that are not very well understood

• AFAIK neurology is just not that good of a field yet

Neurology should in principle be able to completely settle what causes transness. But what are the commonly proposed causes? Here's two theories that I've seen discussed a lot:

• Feminine essence: Some sort of "identity essence" in the brain, such as a neurological body map, can be either male or female, and trans women are males who have been born with a female version of this essence.

• Blanchardian: Among gynephilic trans women, the primary cause is autogynephilia, a sexual attraction to being a woman, whereas among androphilic trans women, the cause is unknown, probably similar to the feminine essence but more malleable than the feminine essence model would suggest.

Beyond these two, I also want to introduce three other theories that can be considered plausible:

• Neither: Something else, e.g. massive polycausality, explains trans women, and the previously mentioned factors are either epiphenomena or only account for a small fraction of trans women.

• Feminine autogynephilia: Similar to the feminine essence theory, there is a part of the brain that is feminized and causes a feminine gender identity. But the important part of the brain is specifically a part of one's sexuality, and the same aspect of sexuality that e.g. autogynephilic cis men have, so the theory doesn't entirely differ from the Blanchardian model either.

• Just autogynephilia: Like in the Blanchardian model and unlike in the feminine autogynephilia model, autogynephilia is the major cause of transsexuality among gynephilic trans women. But unlike the Blanchardian model, it is also the major cause of transsexuality among androphilic trans women.

If a good neurological study is performed that proves one of these theories, then the market will resolve to the corresponding theory. If a very good genetic study or other study proves one of these theories, and people stop investigating it neurologically for some reason, then the market will resolve to the corresponding theory. If no theory gets proven then the market doesn't resolve. If it becomes unresolvable (e.g. all of humanity gets uploaded to computers through some means that doesn't preserve information about how transsexuality works) then the market resolves N/A.

If repression or social contagion (ROGD) plays a role, then repression or social contagion will not be counted, and we will instead consider the other factors residual for repression or social contagion.

I won't be trading in this market.